1. Field of the Invention
The present invention relates generally to an automatic transaxle for a power train of an automotive vehicle. More specifically, the invention relates to a supporting structure for an output shaft of an automotive automatic transaxle.
2. Description of the Background Art
One of the typical construction of the supporting structure for the output shaft of an automotive automatic transaxle has been disclosed in "Automatic Transaxle RN4F02A type, RL4F02A type, 1984 Service Manual" (Nissan Motor Co., Ltd), page 10. The shown automatic transaxle has a counter shaft in parallel to the output shaft. The counter shaft is coupled with the output shaft by an output gear integrally formed with or rigidly secured on the output shaft and a counter gear rigidly secured on the counter shaft. The counter shaft is connected to a differential gear mechanism. The output shaft is supported by means of two tapered roller bearings.
Another typical construction of the automotive automatic transaxle has been disclosed in "A240 type AT Explanation", Toyota Motor Co., Ltd. In the latter publication, the output shaft of the automatic transaxle is supported by means of two ball bearings.
In the former case, the tapered roller bearings tend to be subject to substantial load to cause substantial wearing for lowering power transmission efficiency. Furthermore, since the diameter of the tapered roller bearing arranged at the side of the power transmission section is relatively large, it limits arrangement of clutch, brake and other components designed to be arranged therearound.
In the latter case, since the output shaft is supported only by the ball bearings arranged in the vicinity of both ends. In order to provide sufficient bending strength, the ball bearing has to be arranged at approximately even distance from the associated end of the output shaft. This requires substantial length in axial direction of the output shaft. This also limits reduction of the size of the transaxle unit.